Earth surveying for improved drilling applications

ABSTRACT

Methods and apparatuses for geophysical surveying are disclosed. In one embodiment, a marine vehicle may obtain magnetic measurements in a location around a drilling site. The magnetic measurements may be used to calculate a localized disturbance magnetic field resulting from, for example, solar flares. The localized disturbance magnetic field may be used to calculate a declination value and, thus, a wellbore position with improved accuracy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority of U.S. Provisional PatentApplication No. 61/828,584 filed May 29, 2013 and entitled “EARTHSURVEYING FOR IMPROVED DRILLING APPLICATIONS,” which is herebyincorporated by reference.

BACKGROUND

Wellbore position accuracy ensures successful drilling at a drillingsite to a geological target, such as an underground reservoir of fluidsincluding oil. Magnetic surveying of the area near the drilling site mayimprove an operator's ability to safely reach the geological target. Oneconventional technique is to use a model of Earth's magnetic field tocalculate wellbore position. For example, the International GeomagneticReference Field (IGRF) has been used as magnetic models. However, thesemagnetic models are not accurate enough to provide detailed magneticinformation for a particular localized area near a drilling site. Forexample, in the presence of solar activity, these geomagnetic models areunable to provide accurate localized magnetic field values around theworld.

SUMMARY

In some embodiments, localized magnetic field measurements may beobtained near a drilling site, or other location, from a marine vehicleconfigured with a magnetic measurement device. In some embodiments, themarine vehicle may be a small, automated, unmanned robot with towed orhull-mounted sensors, including magnetic measurement devices. In oneembodiment, the magnetic measurement device is attached to a tow wireand towed behind the marine vehicle. The marine vehicle may beprogrammed with a grid pattern to measure near a drilling site. Whentracing the grid pattern, the marine vehicle may transmit magneticmeasurements to another location, such as a magnetic observatory. Insome embodiments, the magnetic measurements may be obtained in real-time(or near-real time) and utilized in modeling with a network of magneticobservatories and forward surface measurement to extend the range fromone magnetic observatory, such as the nearest observatory orobservatories, to the area of interest.

In one embodiment, a method may include receiving a magnetic field for alocation from a vehicle at the location. The method may also includecalculating a localized magnetic disturbance based, at least in part, onthe received magnetic field. The method may further include calculatinga wellbore position based, at least in part, on the calculated localizedmagnetic disturbance.

In another embodiment, an apparatus may include a marine vehicle. Theapparatus may also include a magnetic measurement device attached to themarine vehicle. The apparatus may further include a processing systemattached to the marine vehicle, the processing system configured toreceive magnetic measurements from the magnetic measurement device andto transmit the magnetic measurements to a magnetic observatory.

In a further embodiment, a system may include a network of magneticobservatories. The system may also include at least one marine vehiclehaving a magnetic measurement device. The system may further include aprocessing station configured to receive magnetic measurements from thenetwork of magnetic observatories and the at least one marine vehicle.The processing system may include a memory for storing the receivedmagnetic measurements and a processor coupled to the memory. Theprocessor may be configured to perform the steps of processing thereceived magnetic measurements and calculating a localized disturbancefield in an area local to a magnetic measurement obtained by the atleast one marine vehicle.

The foregoing has outlined rather broadly certain features and technicaladvantages of some embodiments of the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter that form thesubject of the claims. It should be appreciated by those having ordinaryskill in the art that the specific embodiments disclosed may be readilyutilized as a basis for modifying or designing other structures forcarrying out the same or similar purposes. It should also be realizedthat such equivalent constructions do not depart from the spirit andscope of the invention as set forth in the appended claims. The novelfeatures that are believed to be characteristic of the disclosure, bothas to its organization and method of operation, together with furtherobjects and advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.It is to be expressly understood, however, that each of the figures isprovided for the purpose of illustration and description only and is notintended as a definition of the limits of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed system and methods,reference is now made to the following descriptions taken in conjunctionwith the accompanying drawings.

FIG. 1 is a perspective view of a marine vehicle with a towed magneticmeasurement device according to one embodiment of the disclosure.

FIG. 2 is a map illustrating a system of magnetic observatories andmarine vehicles for supporting a drilling site according to oneembodiment of the disclosure.

FIG. 3 is a flow chart illustrating a method of calculating a wellboreposition according to one embodiment of the disclosure.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a marine vehicle with a towed magneticmeasurement device according to one embodiment of the disclosure. Amarine vehicle 100 may include a hull 102, a mast assembly 104, and apayload section 106. The payload section 106 may include, for example, aprocessing system coupled to an antenna on the mast assembly 104. A sub110 may be attached to the hull 102 by an umbilical cord 108. Theumbilical cord 108 may include cables to facilitate power transmissionand communications between the processing system in the payload section106 with electronic devices on the sub 110. A magnetic measurementdevice 114, such as a magnetometer, may be attached to the sub 110 by atow wire 112. The magnetic measurement device 114 may also be directlyattached to the hull 102 by a tow wire or mounted to the hull 102. Themagnetic measurement device 114 may include magnetometers for scientificseaborne applications, bi-axial horizontal and/or vertical magnetometersystems, and/or automated true-north tri-axial magnetometer systems. Thetow wire 112 may likewise facilitate power transmission andcommunications between the processing system in the payload section 106and the magnetic measurement device 114. The marine vehicle 100 may havea magnetic signature that has a negligible effect on magneticmeasurements obtained by the magnetic measurement device 114. In oneembodiment, the marine vehicle 100 may be constructed entirely ofnon-magnetic materials.

The hull 102 may include solar panels (not shown) for generating powerand a battery (not shown) in the payload section 106 for storing powerfrom the solar panels, to allow twenty-four hour operation of the marinevehicle 100. The solar panels and battery may be configured to keep themarine vehicle 100 in operation for approximately two to three weeks, orlonger.

A rudder 116 on the hull 102 may be controlled by the processing systemto navigate the marine vehicle 100 near a drilling site for obtainingmagnetic measurements of a localized magnetic disturbance field. Forexample, the processing system may control the rudder 116 to navigatethe marine vehicle 100 in a grid search pattern around the drillingsite. In another example, the processing system may receive commandsfrom a remote location, such as the drilling site or magneticobservatory, instructing the marine vehicle to proceed to a particulardestination and control the rudder 116 appropriately. The payloadsection 106 may be fitted with a global positioning system (GPS)receiver to provide accurate or improved location information to theprocessing system.

The processing system may obtain magnetic field measurements from themagnetic measurement device 114 and store or transmit the magnetic fieldmeasurements. The magnetic field measurements may be tagged withlocation information from the GPS receiver. If the measurements arestored by the processing system, the marine vehicle 100 may later beretrieved and the data downloaded from a memory of the processingsystem. If the measurements are transmitted, the processing system mayinclude a wireless transmitter configured to transmit the magneticmeasurements to a remote location, such as to a nearby magneticobservatory or the drilling site.

The payload section 106 may also be loaded with additional sensordevices to provide a suite of one or more services including, but notlimited to, metrological, oceanographic, bathymetric, deep water dataharvesting from subsea structures and seabeds, hydrocarbon seep mapping,turbidity measurements, marine mammal monitoring, source signatureprocessing and water column profiling. In some embodiments, magneticsurveying may be performed in combination with a geophysical survey.

The marine vehicle of FIG. 1 may be implemented in a system formeasuring magnetic fields near a drilling site. FIG. 2 is a mapillustrating a system of magnetic observatories and marine vehicles forsupporting a drilling site according to one embodiment of thedisclosure. A system 200 may include a network of magnetic observatories202A, 202B near a drilling site 204. A fleet of marine vehicles 206A,206B may also be deployed near the drilling site 204. The magneticobservatories 202A may obtain general magnetic measurements for the areanear the drilling site 204, such as by consulting magnetic models and/orother data available. The marine vehicles 206A, 206B may be deployednear the drilling site 204 to obtain localized magnetic measurementsnear the drilling site 204 to improve the accuracy of calculatedmagnetic fields at the drilling site 204, and consequently to improvethe accuracy of wellbore positioning at the drilling site 204.

The marine vehicles 206A, 206B may transmit magnetic measurements to aprocessing station at the magnetic observatories 202A, 202B, or toanother facility, such as a processing system at the drilling site 204.When the magnetic measurements are received, the wellbore position maybe re-calculated and operations at the drilling site 204 adjusted basedon the new calculation. One method utilizing the localized magneticmeasurements is described with reference to FIG. 3 below.

FIG. 3 is a flow chart illustrating a method of calculating a wellboreposition according to one embodiment of the disclosure. A method 300begins at block 302 with receiving a magnetic field measured by a marinevehicle at a location, such as a location near a drilling site or apotential wellbore. According to one embodiment, a marine vehicle, suchas that of FIG. 1, may acquire data in one second intervals utilizingGPS triggers and transmit them to a processing station at one minuteintervals. The magnetic measurements received by the processing stationmay be made available for remote viewing or access, which in someembodiments may be through a web interface.

At block 304, a localized magnetic disturbance for the location iscalculated based, at least in part, on the received magnetic fieldmeasurements of block 302. A total magnetic field (TMI), which ismeasured by the marine vessel at the location, may include threecomponents, a main field, B_(M), a crustal field, B_(C), and a localdisturbance field, B_(D). The main field, B_(M), and the crustal field,B_(C), may be modeled for the location or be derived from the continuousmonitoring at the location by fitting the spline with knot separations,where the spline is the sum of the B_(M) and B_(C). Thus, the differencebetween the measured magnetic field at the location and the sum of themain field, B_(M), and the crustal field, B_(C), is the localdisturbance field, B_(D). The disturbance field, B_(D), may be theresult of, for example, solar flares that alter the Earth's magneticfields.

At block 306, a wellbore position may be calculated based, at least inpart, on the calculated localized magnetic disturbance field, B_(D), ofblock 304. For example, the total magnetic field (TMI), which includesthe calculated localized magnetic disturbance field, B_(D), may be usedto calculate a declination value, which is the difference betweenmagnetic north and true north. The declination value may be used byoperators of a drilling site to direct the drilling operations to reachthe underground reservoir.

The use of a marine vehicle for obtaining localized magneticmeasurements near a drilling site or other location may reduce the riskand high fixed-asset investment in obtaining determining wellborepositions. The marine vehicle may operate unmanned in locations hostileto human life or difficult for humans to access. For example, theunmanned marine vehicle reduces or eliminates crew exposure to piracy orneed for search and rescue (SAR) assets, when compared to traditionalseaborne or airborne magnetic acquisition operations.

The method described with reference to FIG. 3 may be carried out by aprocessing station, located at the drilling site, the magneticobservatory, or another location; or via distributed computing systemssituated at multiple locations. The processing station may include amemory for storing received magnetic measurements and other data and mayinclude a processor coupled to the memory for executing the processingof the received magnetic measurements.

If implemented in firmware and/or software, the functions describedabove may be stored as one or more instructions or code on acomputer-readable medium. Examples include non-transitorycomputer-readable media encoded with a data structure andcomputer-readable media encoded with a computer program.Computer-readable media includes physical computer storage media. Astorage medium may be any available medium that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to store desired program code in the formof instructions or data structures and that can be accessed by acomputer. Disk and disc includes compact discs (CD), laser discs,optical discs, digital versatile discs (DVD), floppy disks and Blu-raydiscs. Combinations of the above should also be included within thescope of computer-readable media.

In addition to storage on computer readable medium, instructions and/ordata may be provided as signals on transmission media included in acommunication apparatus. For example, a communication apparatus mayinclude a transceiver having signals indicative of instructions anddata. The instructions and data are configured to cause one or moreprocessors to implement the functions outlined in the claims.

Although the present disclosure and certain of its advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. Moreover, the scope of the present application is not intendedto be limited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the present invention, disclosure, machines,manufacture, compositions of matter, means, methods, or steps, presentlyexisting or later to be developed that perform substantially the samefunction or achieve substantially the same result as the correspondingembodiments described herein may be utilized according to the presentdisclosure. Accordingly, the appended claims are intended to includewithin their scope such processes, machines, manufacture, compositionsof matter, means, methods, or steps.

What is claimed is:
 1. A method, comprising: receiving a magnetic fieldmeasurement for a location from a vehicle at the location, wherein themagnetic field corresponds to measurements below a surface level;monitoring a magnetic field at the location to determine a crustal fieldat the location; calculating a localized magnetic disturbance related tosolar activity and independent of a main field and independent of thecrustal field based, at least in part, on the received magnetic fieldmeasurement by subtracting the magnetic field measurement from thecrustal field; and calculating a wellbore position based, at least inpart, on the calculated localized magnetic disturbance.
 2. The method ofclaim 1, further comprising receiving a plurality of measured magneticfield values for a plurality of locations arranged along a grid pattern.3. The method of claim 1, in which the step of calculating a localizedmagnetic disturbance comprises: calculating a main field; andcalculating the localized magnetic disturbance based on the main fieldand the crustal field.
 4. The method of claim 1, further comprisingcalculating a declination based, at least in part, on the calculatedlocalized magnetic disturbance.
 5. The method of claim 1, in which thestep of receiving the magnetic field measurement comprises receiving themagnetic field measurement in real-time.
 6. An apparatus, comprising: amarine vehicle; a magnetic measurement device, the magnetic measurementdevice configured to obtain magnetic measurements below a surface levelfor drilling calculations, the magnetic measurement device attached tothe marine vehicle, and wherein the marine vehicle is configured tomonitor a magnetic field at a location to determine a crustal field atthe location; a processing system attached to the marine vehicle, theprocessing system configured to receive magnetic measurements from themagnetic measurement device and to transmit the magnetic measurements toa magnetic observatory for calculating a wellbore position based, atleast in part, on a calculated localized magnetic disturbance related tosolar activity and independent of a main field and independent of thecrustal field, wherein the calculated localized magnetic disturbance iscalculated by subtracting a magnetic field measurement of the magneticmeasurements from the determined crustal field.
 7. The apparatus ofclaim 6, in which the magnetic measurement device is attached to themarine vehicle by a tow wire.
 8. The apparatus of claim 6, in which themarine vehicle comprises a non-magnetic material.
 9. The apparatus ofclaim 6, further comprising at least one of a metrological, anoceanographic, and a bathymetric sensor.
 10. The apparatus of claim 6,further comprising a guidance system configured to propel the marinevehicle through a grid pattern.
 11. The apparatus of claim 6, in whichthe processing system is configured to transmit the magneticmeasurements in real-time.
 12. A system, comprising: at least one marinevehicle having a magnetic measurement device for obtaining magneticmeasurements below a surface level for drilling calculations; and aprocessing station configured to receive magnetic measurements from theat least one marine vehicle, the processing station comprising: a memoryfor storing the received magnetic measurements; and a processor, inwhich the processor is configured to perform the steps of: processingthe received magnetic measurements; determining a crustal field based onthe received magnetic measurements; calculating a localized magneticdisturbance field in an area local to a magnetic measurement related tosolar activity and independent of a main field and independent of thecrustal field by subtracting one of the received magnetic measurementsfrom the determined crustal field; and calculating a wellbore positionbased, at least in part, on the calculated localized magneticdisturbance field.
 13. The system of claim 12, in which the magneticmeasurement device is attached to the at least one marine vehicle by atow wire.
 14. The system of claim 12, in which the at least one marinevehicle further comprises a guidance system configured to propel themarine vehicle through a grid pattern.
 15. The system of claim 12, inwhich the at least one marine vehicle further comprises at least one ofa metrological, an oceanographic, and a bathymetric sensor.
 16. Thesystem of claim 12, in which the at least one marine vehicle isconfigured to transmit the magnetic measurements in real-time.
 17. Thesystem of claim 12, in which the processor is further configured toperform the steps of: calculating a main field; and calculating thelocalized magnetic disturbance based on the main field and the crustalfield.
 18. The method of claim 1, wherein the step of monitoring amagnetic field at the location to determine a crustal field at thelocation comprises monitoring the location by fitting a spline with knotseparations, wherein the spline is the sum of a main field and thecrustal field.
 19. The system of claim 12, wherein the step ofdetermining the crustal field comprises monitoring the location byfitting a spline with knot separations, wherein the spline is the sum ofa main field and the crustal field.